Nicholas O. Tiron (died 1306 × 1307), Abbot of Arbroath and Bishop of Dunblane, was a late 13th-century and early 14th-century churchman in the Kingdom of Scotland.

Little is known about Nicholas until he appeared on 21 November 1299, holding the position of Abbot of Arbroath in a charter of that abbey; the last attestation of his predecessor Henry can be dated to 16 October 1296, so that Nicholas must have become abbot sometime in between these two dates.

[1] As Abbot of Arbroath, he was a canon of Dunblane Cathedral, and entitled to participate in episcopal elections.

[4] When no other turned up, the Pope authorised Nicholas' provision, and he was consecrated by Theodoric, Bishop of Palestrina, on 13 November 1301.

In the events of the early Wars of Scottish Independence, Nicholas' role is unclear and aside from some appearances in the charters of Coupar Angus Abbey, his name is largely absent from the evidence.